A loudspeaker is an acoustic system that typically includes a speaker enclosure, at least one driver, and a crossover network. A loudspeaker driver is an electroacoustic transducer that converts an electrical audio signal into a corresponding sound. The dynamic loudspeaker driver is the most widely used type. When an alternating current electrical audio signal is applied to its voice coil (a coil of wire suspended in a circular gap between the poles of a permanent magnet), the voice coil is forced to move rapidly back and forth due to Faraday's law of induction, which causes a diaphragm (usually conically shaped) attached to the coil to move back and forth, pushing on the air to create sound waves.
A direct radiator loudspeaker has primarily two regions of operation—the pistonic region and the adjacent upper decade of spectrum. The pistonic region is defined as the frequency range between the mechanical resonance of the loudspeaker (i.e., the lower limit) to the spectrum region where wavelength equals the radiating surface (or diaphragm) of the loudspeaker (i.e., the upper limit). The pistonic region is the optimum region of operation for a direct radiator. The adjacent upper decade of spectrum—where wavelength is smaller than the radiating device—has efficient energy output but is flawed by mechanical cone break-up modes and erratic directivity behavior. This region, while flawed, is important in many designs and is the critical region of operation for one or more embodiments of the present disclosure.
The majority of all loudspeaker designs are simple two-way designs, which means they include two radiating elements (called drivers)—a high frequency driver (HF) and a low frequency driver (LF). This design choice is popular due to moderate cost, design simplicity, and moderate package size. This two-way arrangement is also the minimum number of elements that can reproduce the musical spectrum effectively. Within the professional loudspeaker marketplace, larger LF drivers (e.g., >10 inches) are often favored because of improved low frequency performance and overall acoustical output. In this case, the region above pistonic behavior has to be utilized.